Stained glass consists of colored dyes mixed with silicon dioxide molecules. Variations in the color of the glass occur because the dyes often do not mix completely with the silicon dioxide. Stained glass is

A homogeneous mixture has the same composition throughout. Since the dyes do not mix completely with the silicon dioxide, the glass has variations in color and composition from place to place. Therefore, stained glass is heterogeneous.

AI-written and checked against the verified answer.